Data communication over a power line

ABSTRACT

Data signals are communicated between a power line and a computer, wherein the power line provides power to the computer via a distribution transformer and the computer is in communication with a wireless communication path. A first data signal is communicated with the power line. A conversion is made between the first data signal and a second data signal capable of being communicated wirelessly. The second data signal is wirelessly communicated with the wireless communication path.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/075,708, entitled “Data Communication over a Power Line”,filed Feb. 14, 2002, which claims priority under 35 U.S.C. §119(e) ofU.S. Provisional Patent Application Serial No. 60/268,519 and of U.S.Provisional Patent Application Serial No. 60/268,578, both filed Feb.14, 2001.

FIELD OF THE INVENTION

[0002] The invention generally relates to data communication over powerlines and more particularly, to devices and methods for communicatingdata signals with the power lines.

BACKGROUND OF THE INVENTION

[0003] A well-established power distribution system exists throughoutmost of the United States and other countries. The power distributionsystem provides power to customers via power lines. With somemodification, the infrastructure of the existing power distributionsystem can be used to provide data communication in addition to powerdelivery. That is, data signals can be carried by the existing powerlines that already have been run to many homes and offices. The use ofthe existing power lines may help reduce the cost of implementing a datacommunication system. To implement the data communication system, datasignals are communicated to and from the power line at various points inthe power distribution system, such as, for example, near homes,offices, Internet service providers, and like.

[0004] While the concept may sound simple, there are many challenges toovercome before using power lines for data communication. For example, asufficient signal-to-noise ratio should be maintained, a sufficient datatransfer rate should be maintained (e.g., 10 Mbps), “add on” devicesshould be installable without significantly disrupting power supply topower customers, “add on” devices should be designed to withstandoutdoor conditions, bi-directional data communication should besupported, data communication system customers should be protected fromthe voltages present on power lines, and the like.

[0005] Power system transformers are one obstacle to using powerdistribution lines for data communication. Transformers convert voltagesbetween power distribution system portions. For example, a powerdistribution system may include a high voltage portion, a medium voltageportion, and a low voltage portion and a transformers converts thevoltages between these portions. Transformers, however, act as alow-pass filter, passing low frequency signals (e.g., 50 or 60 Hz powersignals) and impeding high frequency signals (e.g., frequenciestypically used for data communication) from passing through thetransformer. As such, a data communication system using power lines fordata transmission faces a challenge in passing the data signals from thepower lines a to customer premise.

[0006] Moreover, accessing data signals on a power lines is a potentialsafety concern. Medium voltage power lines can operate from about 1000 Vto about 100 kV which can generate high current flows. As such, anyelectrical coupling to a medium voltage power line is a concern.Therefore, a need exists for a device that can safely communicate datasignals with a medium voltage power line and yet provide electricalisolation from the medium voltage power line.

[0007] In addition to communicating a data signal with a medium voltagepower line, it would be advantageous to communicate the data signal to acustomer premise. That is, a need also exists for a device thatelectrically communicates a data signal between a medium voltage powerline and a low voltage power line, while maintaining electricalisolation between the medium voltage power line and the low voltagepower line.

SUMMARY OF THE INVENTION

[0008] The invention is directed to communicating data signals with apower line and wirelessly communicating the data signals to a computer,wherein the power line feeds power to the computer via a distributiontransformer. A first data signal is communicated with the power line,wherein the first data signal is an analog data signal capable of beingcarried by the power line. A conversion is made between the first datasignal and a second data signal capable of being transmitted wirelesslyto the computer. The second data signal is wirelessly communicated withthe computer.

[0009] The first data signal may be inductively communicated with thepower line. The converting may comprise modulating and demodulating thefirst data signal with Orthogonal Frequency Division Multiplexing androuting the first data signal. The converting may further compriseconverting the first data signal to a radio frequency signal, to amicrowave frequency signal, to a signal formatted in compliance with anIEEE 802.11 protocol, to a light data signal and then to a wireless datasignal, and to an acoustic frequency signal.

[0010] The first data signal may be received from the power line andconverted to a data signal capable of being transmitted wirelessly tothe computer and then be transmitted to the computer. The second datasignal may be wirelessly received from the computer, converted to ananalog data signal capable of being carried by the power line andcommunicated to the power line.

[0011] A system for communicating data between a power line and acomputer includes a coupling device, a signal converter, and a wirelesstransceiver. The coupling device couples to the power line andcommunicates a first data signal with the power line. The signalconverter communicates with the coupling device and converts between thefirst data signal and a second data signal capable of being transmittedwirelessly to the computer. The wireless transceiver wirelesslycommunicates the second data signal with the computer.

[0012] The coupling device may comprise an inductor. The signalconverter may comprise a modem, a data router, an optoelectronictransceiver, a radio frequency transceiver, a microwave frequencytransceiver, an antenna, and an acoustic transceiver.

[0013] The above-listed features, as well as other features, of theinvention will be more fully set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention is further described in the detailed descriptionthat follows, by reference to the noted drawings by way of non-limitingillustrative embodiments of the invention, in which like referencenumerals represent similar parts throughout the drawings. As should beunderstood, however, the invention is not limited to the precisearrangements and instrumentalities shown. In the drawings:

[0015]FIG. 1 is a diagram of an exemplary power distribution system withwhich the invention may be employed;

[0016]FIG. 2 is a diagram of the exemplary power distribution system ofFIG. 1 modified to operate as a data communication system, in accordancewith an embodiment of the invention;

[0017]FIG. 3 is a block diagram of a portion of a data communicationsystem, in accordance with an embodiment of the invention;

[0018]FIG. 4 is a block diagram of a portion of a data communicationsystem, in accordance with an embodiment of the invention;

[0019]FIG. 5 is a perspective view of a power line coupler and a powerline bridge installed at a telephone pole of a power distributionsystem, in accordance with an embodiment of the invention;

[0020]FIG. 6 is a schematic of a power line coupler, in accordance withan embodiment of the invention;

[0021]FIG. 7 is a schematic of another power line coupler, in accordancewith another embodiment of the invention;

[0022]FIG. 8 is a diagram of another portion of a data communicationsystem, in accordance with another embodiment of the invention; and

[0023]FIG. 9 is a flow diagram of an illustrative method for datacommunication over a power line, in accordance with an embodiment of theinvention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0024] A power line coupler and a power line bridge communicate datasignals across a transformer that would otherwise filter the datasignals from passing through the transformer. Further, the power linecoupler provides high electrical isolation between the transformerprimary side and secondary side, thereby preventing substantial powerflow through the power line coupler and the power line bridge. It shouldbe appreciated that the functionality of the power line coupler and thepower line bridge can be included in one device or distributed in morethan one device. The power line coupler may include a power linecoupling device that communicates data signals with a power line,circuitry to condition the data signal, circuitry to handlebi-directional signal transfer, circuitry to enable the use of anelectrical isolator, circuitry to provide operational power from thepower line, and may be designed to be self-contained. The power linecoupler may include circuitry to communicate with the power line couplerand circuitry to convert data signals to a second format forcommunication to a customer premise.

[0025] An exemplary power distribution system is shown in FIG. 1. Asshown in FIG. 1, power distribution system 100 is a medium voltage halfloop power distribution system that is common to the United States. Theinvention, however, may be employed with other power distributionsystems, such as, for example, a high voltage delivery system that iscommon to European countries, as well as other power distributionsystems.

[0026] Power distribution system 100 includes components for powergeneration and power transmission and delivery. As shown in FIG. 1, apower generation source 101 is a facility that produces electric power.Power generation source 101 includes a generator (not shown) thatcreates the electrical power. The generator may be a gas turbine or asteam turbine operated by burning coal, oil, natural gas, or a nuclearreactor, for example. Power generation source 101 typically providesthree-phase AC power. The generated AC power typically has a voltage ashigh as approximately 25,000 volts.

[0027] A transmission substation (not shown) increases the voltage frompower generation source 101 to high-voltage levels for long distancetransmission on high-voltage transmission lines 102. Typical voltagesfound on high-voltage transmission lines 102 range from 69 to in excessof 800 kilovolts (kV). High-voltage transmission lines 102 are supportedby high-voltage transmission towers 103. High-voltage transmissiontowers 103 are large metal support structures attached to the earth, soas to support the transmission lines and provide a ground potential tosystem 100. High-voltage transmission lines 102 carry the electric powerfrom power generation source 101 to a substation 104.

[0028] In addition to high-voltage transmission lines 102, powerdistribution system 100 includes medium voltage power lines 120 and lowvoltage power line 113. Medium voltage is typically from about 1000 V toabout 100 kV and low voltage is typically from about 100 V to about 240V. As can be seen, power distribution systems typically have differentvoltage portions. Transformers are often used to convert between therespective voltage portions, e.g., between the high voltage portion andthe medium voltage portion and between the medium voltage portion andthe low voltage portion. Transformers have a primary side for connectionto a first voltage and a secondary side for outputting another (usuallylower) voltage. Transformers are often referred to as a step downtransformers because they typically “step down” the voltage to somelower voltage. Transformers, therefore, provide voltage conversion forthe power distribution system. This is convenient for power distributionbut inconvenient for data communication because the transformers candegrade data signals, as described in more detail below.

[0029] A substation transformer 107 is located at substation 104.Substation 104 acts as a distribution point in system 100 and substationtransformer 107 steps-down voltages to reduced voltage levels.Specifically, substation transformer 107 converts the power onhigh-voltage transmission lines 102 from high voltage levels to mediumvoltage levels for medium voltage power lines 120. In addition,substation 104 may include an electrical bus (not shown) that serves toroute the medium voltage power in multiple directions. Furthermore,substation 104 often includes circuit breakers and switches (not shown)that permit substation 104 to be disconnected from high-voltagetransmission lines 102, when a fault occurs on the lines.

[0030] Substation 104 typically is connected to at least onedistribution transformer 105. Distribution transformer 105 may be apole-top transformer located on a utility pole, a pad-mountedtransformer located on the ground, or a transformer located under groundlevel. Distribution transformer 105 steps down the voltage to levelsrequired by a customer premise 106, for example. Power is carried fromsubstation transformer 107 to distribution transformer 105 over one ormore medium voltage power lines 120. Power is carried from distributiontransformer 105 to customer premise 106 via one or more low voltagelines 113. Also, distribution transformer 105 may function to distributeone, two, three, or more phase currents to customer premise 106,depending upon the demands of the user. In the United States, forexample, these local distribution transformers typically feed anywherefrom one to ten homes, depending upon the concentration of the customerpremises in a particular location.

[0031] Transformer 105 converts the medium voltage power to low voltagepower. Transformer 105 is electrically connected to medium voltage powerlines 120 on the primary side of the transformer and low voltage powerlines 113 on the secondary side of the transformer. Transformers act asa low-pass filter, passing low frequency signals (e.g., 50 or 60 Hzpower signals) and impeding high frequency signals (e.g., frequenciestypically used for data communication) from passing from the transformerprimary side to the transformer secondary side. As such, a datacommunication system using power lines 120 for data transmission faces achallenge in passing the data signals from the medium voltage powerlines 120 to customer premises 106.

[0032]FIG. 2 illustrates the power distribution system of FIG. 1 asmodified for operation as a data communication system, in accordancewith an embodiment of the invention. As described above, a powerdistribution system is typically separated into high voltage powerlines, medium voltage power lines, and low voltage power lines thatextend to customer premises 106. The high voltage power lines typicallyhave the least amount of noise and least amount of reflections. Thesehigh voltage power lines have the highest potential bandwidth for datacommunications. This is convenient because it is the portion thatconcentrates the bandwidth from the other low and medium voltageportions. The type of signal modulation used on this portion can bealmost any signal modulation used in communications (Code DivisionMultiple Access (CDMA), Time Division Multiple Access (TDMA), FrequencyDivision Multiplex (FDM), Orthogonal Frequency Division Multiplex(OFDM), and the like). Typically, OFDM is used on both the low andmedium voltage portions. A modulation producing a wideband signal suchas CDMA that is relatively flat in the spectral domain may be used toreduce radiated interference to other systems while still deliveringhigh data communication rates.

[0033] Medium voltage power lines 120 and low voltage power lines 113typically have some noise present from electrical appliances andreflections due to the “web” of wires in those portions. Low powervoltage lines 113 often have more noise than medium voltage power lines120. These portions of the power distribution system typically support alower bandwidth than the high voltage power lines and therefore, usuallyemploy a more intelligent modulation scheme (typically with moreoverhead). There are several companies with commercially available chipsets to perform modulation schemes for local area networks (LANs) suchas, for example: Adaptive Networks (Newton, Mass.), Inari (Draper,Utah), Intellion (Ocala, Fla.), DS2 (Valencia, Spain) and Itran(Beer-Sheva, Israel).

[0034] As shown in FIG. 2, a power line coupler 200 communicates withmedium voltage power line 120 and a power line bridge 210 communicateswith low voltage power line 113. Further, power line coupler 200 andpower line bridge 210 communicate with each other to allow data signalsto bypass transformer 105, as described in more detail below. A powerline interface device 250 can plug into an electrical outlet andoperates to allow customers to access the data signal on the low voltagepower line 113. An aggregation point 220 operates to allow a serviceprovider to access data signals on medium voltage power line 120. Itshould be appreciated that although power line coupler 200 and powerline bridge 210 are shown in FIG. 2 as being located at a specificlocation, the power line coupler and the power line bridge functionalitymay be located in various locations on the power system.

[0035] Returning to power line coupler 200 and power line bridge 210,FIG. 3 illustrates an example of their operation. As described above,bridging data signals between portions of the power distribution systemcan be a problem, because of the low pass filtering aspect of atransformer. To overcome the problem, power line coupler 200 and powerline bridge 210 form an electrically non-conductive path 300 forcommunicating non-electrically conducting signals around transformer105, thereby bypassing the low-pass filtering of transformer 105. Whileelectrically non-conductive path 300 does not pass significant amountsof power, it does allow data signals to bypass transformer 105. That is,power line coupler 200 interfaces data signals to medium voltage powerlines 120 on the primary side of transformer 105 and power line bridge210 interfaces data signals to low voltage power lines 113 on thesecondary side of transformer 105.

[0036] Power line coupler 200 and power line bridge 210 communicate witheach other, thereby allowing data signals to bypass transformer 105,thus avoiding the filtering of the high frequency data signal thatotherwise would occur in transformer 105. Lower frequency power signalscontinue to flow from medium voltage power lines 120 to low voltagepower lines 113 via transformer 105. Power line coupler 200 provideselectrical isolation between medium voltage power lines 120 and lowvoltage power lines 113 by substantially preventing power from flowingover electrically non-conductive path 300.

[0037]FIG. 4, illustrates more detail of power line coupler 200 andpower line bridge 210. As shown in FIG. 4, power line coupler 200includes a power line coupling device 400 and an electricallynon-conductive device 410.

[0038] Power line coupling device 400 communicates data signals withmedium voltage power line 120. Power line coupling device 400 mayinclude, for example, a current transformer, an inductor, a capacitor,an antenna, and the like.

[0039] Electrically non-conductive device 410 provides electricalisolation between medium voltage power lines 120 and low voltage powerlines 113 and communicates non-electrically conducting signals.Electrically non-conductive device 410 may be a fiber optic cable, alight pipe, a sufficiently wide air gap, a sufficiently wide dielectricmaterial, and the like.

[0040] Power line bridge 210 may include a modem 420, a data router 430,a modem 440, an electrically non-conductive device 450, and a power linecoupling device 460.

[0041] Modem 420 modulates and demodulates data signals between powerline coupler 200 and data router 430. Modem 420 typically is selected tooptimize the communication of the data signals over medium voltage powerline 120. For example, modem 420 may be selected to operate with a 50MHz carrier frequency. Further, modem 420 may be selected to use amodulation technique, such as, for example, CDMA, TDMA, FDM, OFDM, andthe like.

[0042] Router 430 routes digital data signals between modem 420 andmodem 440. Router 430 may receive and send data packets, match datapackets with specific messages and destinations, perform traffic controlfunctions, perform usage tracking functions, authorization functions,throughput control functions, and the like.

[0043] Modem 440 modulates and demodulates data signals between powerline coupler 460 and data router 430. Modem 440 typically is selected tooptimize the communication of the data signals over low voltage powerline 113. Modem 440 may be selected to operate with a carrier frequencywithin the range of 2 to 24 MHz, for example. Further, modem 420 may beselected to modulate using a technique, such as, for example, CDMA,TDMA, FDM, OFDM, and the like. The use of modems 420 and 440 allows themodulation technique for each modem to be individually matched to thecharacteristics of the power line with which it communicates. Ifhowever, the same modulation technique is used on both low voltage powerlines 113 and medium voltage power lines 120, modem 420, data router430, and modem 440 may be omitted from power line bridge 210.

[0044] Electrically non-conductive device 450 provides electricalisolation between low voltage power lines 113 and modem 440.Electrically non-conductive device 450 may be a fiber optic cable, alight pipe, a sufficiently wide air gap, a sufficiently wide dielectricmaterial, and the like. Because low voltage power lines 113 operate at alow voltage, electrically non-conductive device 450 may include acapacitor. That is, a capacitor can provide a sufficient electricalisolation between low voltage power lines 113 and a customer. Power linecoupling device 460 may include a current transformer, an inductor, acapacitor, an antenna, and the like.

[0045]FIG. 5 illustrates an installation of power line coupler 200 andpower line bridge 210 to a power distribution system. As shown in FIG.5, power line coupler 200 is mounted proximate medium voltage power line120 and power line bridge 210 is mounted proximate low voltage powerline 113. Power line coupler 200 and power line bridge 210 are incommunication via communication medium 500. Communication medium 500 maybe a fiber optic cable, an air gap, a dielectric material, and the like.

[0046] Power line coupler 200 receives a data signal from medium voltagepower line 120. Power line coupler 100 converts the data signal to anon-electrically conducting signal (i.e., a signal that can betransmitted over a non-electrically conductive path). A non-electricallyconducting signal may be a light signal, a radio frequency signal, amicrowave signal, and the like. Power line coupler 200 transmits thesignal over communication medium 500. Power line bridge 210 receives thenon-electrically conducting signal and conditions the signal forcommunication over low voltage power line 113 to customer premise 106(as discussed with reference to FIG. 2).

[0047] Rather than communicating data signals to customer premise 106via low voltage power line 113, power line bridge 210 may use othercommunication media. FIG. 5 depicts several other techniques forcommunicating data signals to customer premise 106. For example, powerline bridge 210 may convert the data signals to electric data signalsand communicate the electric data signals via telephone line 550 orcoaxial cable line 554. Such communication may be implemented in asimilar fashion to the communication with low voltage power line 113.

[0048] Power line bridge 210 may convert the data signal to radiosignals for communication over a wireless communication link 556. Inthis case, customer premise 106 includes a radio transceiver forcommunicating with wireless communication link 556. In this manner,power line bridge 210 functions as a communication interface, convertingthe non-electrically conducting signal to a signal appropriate forcommunication to customer premise 106. Wireless communication link 556may be a wireless local area network implementing a network protocol inaccordance with the IEEE 802.11 standard.

[0049] Alternatively, light signals may be communicated to customerpremise 106 directly via a fiber optic 552. In this alternativeembodiment, power line bridge may convert the data signals to lightsignals for communication over fiber optic line 552. Alternatively, thedata signals already may be in light form and therefore, power linecoupler may communicate directly with user premise 106. In thisembodiment, customer premise 106 may have a fiber optic connection forcarrying data signals, rather than using the internal wiring of customerpremise 106.

[0050]FIG. 6, illustrates more details of power line coupler 200. Asshown in FIG. 6, power line coupler 200 includes an inductor 602,capacitors 606, transmit circuitry 610, receive circuitry 612, transmitoptoelectronic device 620, and receive optoelectronic device 622.

[0051] Inductor 602 communicates data signals with medium voltage powerline 120 via magnetic coupling. Inductor 602 may be a toroidally shapedinductor that is inductively coupled with medium voltage power line 120.Inductor 602 includes a toroidally shaped magnetic core with windings604 disposed to facilitate flux linkage of the data signal on mediumvoltage power line 120. The number and orientation of windings 604typically is selected for increased flux linkage. Further, thepermeability of the magnetic core typically is selected for highcoupling with the high frequency data signal and a high signal to noiseratio. Also, the permeability characteristics of inductor 602 may beselected to reduce saturation of the core. If the core becomessaturated, the data signal may become “clipped.”

[0052] Medium voltage power line 120 may be disposed through inductor602. To facilitate easy installation and minimal impact to customerservice, inductor 602 may include a hinge. With such a hinge, inductor602 may simply snap around medium voltage power line 120 using existingutility tools and techniques. In this manner, installation of inductor602 can be performed without disrupting power to the power users andwithout stripping any insulation from medium voltage power line 120.

[0053] Inductor 602 is electrically connected to capacitors 606.Capacitors 606 provide some electrical isolation between optoelectronicdevices 620, 622 and inductor 602. Capacitors 606 further providefiltering of the power signal from the data signal. That is, the datasignal, which typically is a high frequency signal, passes acrosscapacitors 606 while the power signal, which typically is a lowerfrequency (e.g., 50 or 60 Hz), is substantially prevented from passingacross capacitors 606. While such filtering need not be implementednecessarily, filtering typically is included to simplify the design ofsystem. Alternatively, such filtering may be implemented elsewherewithin system 200, for example, in transmit circuitry 610, receivecircuitry 612, power line bridge 210, and the like.

[0054] Capacitors 606 are electrically connected to transmit circuitry610 and receive circuitry 612. Transmit circuitry 610 and receivecircuitry 612 may amplify the data signal, filter the data signal,buffer the data signal, modulate and demodulate the signal, and thelike. Transmit circuitry 610 typically is selected to maximize the powerof the data signal to keep the signal-to-noise ratio of the data signalat an acceptable level. Receive circuitry 612 typically includes anamplifier designed to handle the lowest expected received data signallevel. At a system level, the modulation and demodulation techniquestypically are selected to reduce interference between transmit andreceive signals.

[0055] Transmit circuitry 610 and receive circuitry 612 are electricallyconnected to transmit optoelectronic device 620 and receiveoptoelectronic device 622, respectively. Transmit optoelectronic device620 converts a light data signal, for example, from communication medium630 to an electrical data signal for use by transmit circuitry 610.Transmit optoelectronic device 620 may include a light emitting diode, alaser diode, a vertical cavity surface emitting laser, and the like.Receive optoelectronic device 622 converts an electrical data signalfrom receive circuitry 612 to a light data signal for transmissionthrough communication medium 630. Receive optoelectronic device 622 mayinclude a photosensitive diode, photosensitive transistor, and the like.

[0056] Transmit optoelectronic device 620 and receive optoelectronicdevice 622 are in communication with communication medium 630. As shown,light signals are communicated between both transmit circuitry 610 andreceive circuitry 612 and communication medium 630.

[0057] Communication medium 630 communicates light signals between powerline coupler 100 and the power line bridge 210. Communication medium iselectrically nonconductive, thereby breaking the electrically conductivepower path between power line coupler 200 and power line bridge 210.Communication medium 630 may include a light pipe, a fiber-optic cable,and the like.

[0058] In this manner, data signals on the power lines are converted tolight signals and are transmitted over optical communication medium 630.Similarly, light signals from optical communication medium 630 areconverted to electrical signals for communication with the power lines.Communication medium 630, being electrically non-conductive, providesthe increased safety that is desired by many power distributioncompanies by not allowing substantial power to flow throughcommunication medium 630.

[0059] Power line coupler 200 includes a power supply inductor 680 and apower supply 682. Power supply inductor 680, constructed similar toinductor 602, inductively draws power from medium voltage power line120. Power supply inductor 680 typically is selected to have magneticcharacteristics appropriate for coupling power signals from mediumvoltage power line 120. Power supply 682 receives power from inductor680 (e.g., alternating current (ac) power) and converts the power to anappropriate form for use by transmit circuitry 610, receive circuitry612, and the like (e.g., direct current (dc) power). As such, power linecoupler 200 can be a “closed” system, internally deriving its own powerand thereby avoiding the use of batteries (which may be costly andimpractical).

[0060] Power line coupler 200 includes a housing 650 to protect it fromexposure to the environmental conditions. Housing 650 may be constructedwith high dielectric, corrosive resistant materials, fasteners,adhesives, and sealed conduit openings. Housing 650 may further bedesigned to reduce the risk of exposure to the voltage potential presenton medium voltage power line 120.

[0061] In the embodiment illustrated in FIG. 6, communication medium 630is a fiber optic cable that provides electrical isolation between mediumvoltage power line 120 and low voltage power line 113. Othercommunication media may be used to provide such electrical isolation.For example, inductor 602 may include an annularly shaped dielectricmaterial disposed coaxially between medium voltage power line 120 andinductor 602. The dielectric material allows inductor 602 to bemagnetically coupled to medium voltage power line 120, thereby allowingcommunication of data signals. The dielectric material does not allowsignificant power to pass from medium voltage power line 120 to lowvoltage power line 113. Alternatively, rather than converting theelectric data signals to light data signals, power line coupler 200 mayconvert the electric data signals to wireless data signals, such as, forexample, radio frequency signals.

[0062]FIG. 7 illustrates another embodiment of a power line coupler200′. As shown in FIG. 7, power line coupler 200′ includes a radiofrequency (RF) choke 705, capacitors 710, a transformer 720, transmitcircuitry 610, receive circuitry 612, transmit optoelectronic device620, and receive optoelectronic device 622.

[0063] RF choke 705 may be disposed around and is directly connected tomedium voltage power line 120 and may comprise ferrite beads. RF choke705 operates as a low pass filter. That is, low frequency signals (e.g.,a power signal having a frequency of 50 or 60 Hz) pass through RF choke705 relatively unimpeded (i.e., RF choke 705 can be modeled as a shortcircuit to low frequency signals). High frequency signals (e.g., a datasignal), however, do not pass through RF choke 705; rather, they areabsorbed in RF choke 705 (i.e., RF choke 705 can be modeled as an opencircuit to high frequency signals). As such, the voltage across RF choke705 includes data signals but substantially no power signals. Thisvoltage (i.e., the voltage across RF choke 705) is applied totransformer 720 via capacitors 710 to receive data signals from mediumvoltage power line 120. To transmit data signals to medium voltage powerline 120, a data signal is applied to transformer 720, which in turncommunicates the data signal to RF choke 705 through capacitors 710.

[0064] Capacitors 710 provide some electrical isolation between mediumvoltage power line 120 and transformer 720. Capacitors 710 furtherprovides filtering of stray power signals. That is, the data signalpasses across capacitors 710 while any power signal is substantiallyprevented from passing across capacitors 710. Such filtering can beimplemented elsewhere within the system or not implemented at all.

[0065] Transformer 720 may operate as a differential transceiver. Thatis, transformer 720 may operate to repeat data signals received from RFchoke 705 to receive circuitry 612 and to repeat data signals receivedfrom transmit circuitry 610 to RF choke 705. Transformer 720 alsoprovides some electrical isolation between medium voltage power line 120and low voltage power line 113.

[0066] Capacitors 606 may be electrically connected between transmitcircuitry 610 and receive circuitry 612 and transformer 720. Transmitcircuitry 610 and receive circuitry 612 are electrically connected totransmit optoelectronic device 620 and receive optoelectronic device622, respectively. Transmit optoelectronic device 620 and receiveoptoelectronic device 622 are in communication with communication medium630. Power line coupler 200′ may include a power supply inductor 680, apower supply 682, and a housing 650, similar to that shown in FIG. 6.

[0067] In the embodiments illustrated in FIGS. 6 and 7, communicationmedium 630 is a fiber optic cable that provides electrical powerisolation between medium voltage power line 120 and low voltage powerline 113. Other communication media may be used to provide suchelectrical power isolation. For example, inductor 602 may include anannularly shaped dielectric material (not shown) disposed coaxiallywithin inductor 602. The dielectric material allows inductor 602 to bemagnetically coupled to medium voltage power line 120, thereby allowingcommunication of data signals. The dielectric material does not allowsignificant power to pass from medium voltage power line 120 to lowvoltage power line 113. Alternatively, inductor 602 may communicate witha wireless transceiver (not shown) that converts data signals towireless signals. In this case, communication medium 630 is air.

[0068] Returning to FIG. 2, power line coupler 200 communicates datasignals with power line bridge 210, that is turn communicates the datasignals to low voltage power line 113. The data signal carried by lowvoltage power line 113 is then provided to power line interface device250 via low-voltage premise network 130. Power line interface device 250is in communication low-voltage premise network 130 and with variouspremise devices that are capable of communicating over a data network,such as for example, a telephone, a computer, and the like.

[0069] Power line interface device 250 converts a signal provided bypower line bridge 210 to a form appropriate for communication withpremise devices. For example, power line interface device 250 mayconvert an analog signal to a digital signal for receipt at customerpremise 106, and converts a digital signal to an analog signal for datatransmitted by customer premise 106.

[0070] Power line interface device 250 is located at or near theconnection of low voltage power line 113 with customer premise 106. Forexample, power line interface device 250 may be connected to a load sideor supply side of an electrical circuit breaker panel (not shown).Alternatively, power line interface device 250 may be connected to aload side or supply side of an electrical meter (not shown). Therefore,it should be appreciated that power line interface device 250 may belocated inside or outside of customer premise 106.

[0071] A “web” of wires distributes power and data signals withincustomer premise 130. The customer draws power on demand by plugging anappliance into a power outlet. In a similar manner, the user may plugpower line interface device 250 into a power outlet to digitally connectdata appliances to communicate data signals carried by the power wiring.Power line interface device 250 serves as an interface for customer dataappliances (not shown) to access data communication system 200. Powerline interface device 250 can have a variety of interfaces for customerdata appliances. For example, power line interface device 250 caninclude a RJ-11 Plain Old Telephone Service (POTS) connector, an RS-232connector, a USB connector, a 10 Base-T connector, and the like. In thismanner, a customer can connect a variety of data appliances to datacommunication system 200. Further, multiple power line interface devices250 can be plugged into power outlets in the customer premise 130, eachpower line interface device 250 communicating over the same wiring incustomer premise 130.

[0072] In alternative embodiments, rather than using low voltage powerlines 113 to carry the data signals and power line interface device 250to convert the data signals, power line bridge 210 converts data signalsto be carried by another medium, such as, for example, a wireless link,a telephone line, a cable line, a fiber optic line, and the like.

[0073] As described above a customer can access data communicationsystem 200 via power line interface device 250. A service provider,however, typically accesses data communication system 200 viaaggregation point 220, as shown in FIG. 2. FIG. 8 shows more details ofaggregation point 220. As shown in FIG. 8, power line coupling device200 communicates between medium voltage power line 120 and aggregationpoint 220. Aggregation point 220 includes a modem 810, a backhaulinterface 820, and a backhaul link 830 Aggregation point 220 allows aservice provider to access data communication system 200.

[0074]FIG. 9 is a flow diagram of an illustrative method 900 forcommunicating data between medium voltage power line 120 and low voltagepower line 113. As shown in FIG. 9 at step 910, a data signal isreceived from medium voltage power line 120. Typically, the data signalis in the form of a high-frequency electrical signal. At step 920, thedata signal is converted from an electrical signal to a light signal. Atstep 930, the light signal is communicated to a fiber optic cable and atstep 940, the light signal is received. At step 950 the light signal isconverted back to an electric data signal and at step 960, the electricdata signal is communicated to medium voltage power line 120.

[0075] The invention is directed to directed to a power line coupler anda power line bridge that communicate data signals across a transformerthat would otherwise filter the data signals from passing through thetransformer. Further, the power line coupler provides high electricalisolation between the transformer primary side and secondary side. Thepower line coupler can be used to provide data services to residencesand service providers. Possible applications include remote utilitymeter reading, Internet Protocol (IP)-based stereo systems, IP-basedvideo delivery systems, and IP telephony, Internet access, telephony,video conferencing, and video delivery, and the like.

[0076] It is to be understood that the foregoing illustrativeembodiments have been provided merely for the purpose of explanation andare in no way to be construed as limiting of the invention. Words whichhave been used herein are words of description and illustration, ratherthan words of limitation. Further, although the invention has beendescribed herein with reference to particular structure, materialsand/or embodiments, the invention is not intended to be limited to theparticulars disclosed herein. Rather, the invention extends to allfunctionally equivalent structures, methods and uses, such as are withinthe scope of the appended claims. Those skilled in the art, having thebenefit of the teachings of this specification, may affect numerousmodifications thereto and changes may be made without departing from thescope and spirit of the invention.

What is claimed is:
 1. A method of communicating data between a powerline and a computer, the power line providing power to the computer viaa distribution transformer, the computer in communication with awireless communication path, the method comprising: communicating afirst data signal with the power line; converting between said firstdata signal and a second data signal, said second data signal capable ofbeing communicated wirelessly; and wirelessly communicating said seconddata signal through the wireless communication path.
 2. The method asrecited in claim 1, wherein said communicating said first data signalcomprises inductively communicating said first data signal with thepower line.
 3. The method as recited in claim 1, wherein said convertingcomprises modulating and demodulating said first data signal.
 4. Themethod as recited in claim 3, wherein said modulating and demodulatingcomprises modulating and demodulating said first data signal withOrthogonal Frequency Division Multiplexing.
 5. The method as recited inclaim 3, wherein said converting further comprises routing said seconddata signal.
 6. The method as recited in claim 3, wherein saidconverting comprises converting said first data signal to a signalformatted in compliance with an IEEE 802.11 protocol.
 7. The method asrecited in claim 3, wherein said converting comprises converting saidfirst data signal to a light data signal and converting said light datasignal to a wireless data signal.
 8. The method as recited in claim 1,wherein said converting comprises converting said first data signal to asignal formatted in compliance with an IEEE 802.11 protocol.
 9. Themethod as recited in claim 1, wherein said converting comprisesconverting said first data signal to a light data signal and convertingsaid light data signal to a wireless data signal.
 10. The method asrecited in claim 1, wherein said converting comprises converting saidfirst data signal to an acoustic frequency signal.
 11. The method asrecited in claim 1, wherein said communicating said first data signalwith the power line and converting comprise receiving said first datasignal from the power line and converting said received first datasignal to a data signal capable of being transmitted wirelessly to thecomputer.
 12. The method as recited in claim 11, wherein said wirelesslycommunicating said second data signal comprises wirelessly transmittingsaid converted data signal to the computer.
 13. The method as recited inclaim 1, wherein said wirelessly communicating said second data signalcomprises wirelessly receiving said second data signal.
 14. The methodas recited in claim 1, wherein said wirelessly communicating said seconddata signal comprises communicating said second data signal with awireless transceiver.
 15. The method as recited in claim 13, whereinsaid communicating said first data signal with the power line andconverting comprise converting said wirelessly received second datasignal to an analog data signal capable of being carried by the powerline and communicating said analog data signal to the power line.
 16. Asystem for communicating data between a power line and a computer, thepower line providing power to the computer via a distributiontransformer, the computer in communication with a wireless communicationpath, the system comprising: a coupling device that couples to the powerline to communicate a first data signal with the power line; a signalconverter in communication with said coupling device, said signalconverter converts between said first data signal and a second datasignal, said second data signal capable of being communicatedwirelessly; and a wireless communication device in communication withsaid signal converter to wirelessly communicate said second data signalwith the wireless communication path.
 17. The system as recited in claim16, wherein said coupling device comprises an inductor.
 18. The systemas recited in claim 16, wherein said coupling device comprises anantenna.
 19. The system as recited in claim 16, wherein said signalconverter comprises a modem.
 20. The system as recited in claim 19,wherein said signal converter further comprises a data router incommunication with said modem.
 21. The system as recited in claim 16,wherein said signal converter comprises an optoelectronic transceiver.22. The system as recited in claim 16, wherein said wirelesscommunication device comprises a radio frequency transceiver.
 23. Thesystem as recited in claim 16, wherein said wireless communicationdevice comprises a microwave frequency transceiver.
 24. The system asrecited in claim 16, wherein said wireless communication devicecomprises an antenna.
 25. The system as recited in claim 16, whereinsaid wireless communication device comprises an acoustic transceiver.26. The system as recited in claim 16, further comprising aweather-resistant housing containing at least a portion of said signalconverter.
 27. A method of using a power line to provide communicationsbetween a first computer and a second computer, the first computer incommunication with the power line, the second computer in communicationwith a wireless communication path, the method comprising: receiving afirst data signal transmitted through the power line, said first datasignal including data from the first computer; converting said firstdata signal to a second data signal; wirelessly transmitting said seconddata signal through the wireless communication path; wirelesslyreceiving a third data signal, said third data signal being a wirelesstransmission and including data from the second computer; convertingsaid third data signal to a fourth data signal; and transmitting saidfourth data signal through the power line to the first computer.
 28. Themethod as recited in claim 27, wherein said converting said first datasignal to a second data signal comprises demodulating said first datasignal.
 29. The method as recited in claim 28, wherein said demodulatingsaid first data signal comprises demodulating said first data signalwith Orthogonal Frequency Division Multiplexing.
 30. The method asrecited in claim 28, wherein said converting further comprisesconverting said demodulated first data signal to a signal formatted incompliance with an IEEE 802.11 protocol.
 31. The method as recited inclaim 27, wherein said converting said third data signal to a fourthdata signal comprises modulating said third data signal.
 32. The methodas recited in claim 31, wherein said modulating said third data signalcomprises modulating said third data signal with Orthogonal FrequencyDivision Multiplexing.
 33. The method as recited in claim 27, whereinthe power line has a voltage greater than one thousand volts.
 34. Acommunication system for providing communications between a firstcomputer and a second computer, the first computer in communication witha power line, the second computer in communication with a wirelesscommunication path, the system comprising: a coupling device thatcommunicatively couples to the power line to communicate with the firstcomputer through the power line, the communication through the powerline being in a first data format; a signal converter in communicationwith said coupling device, said signal converter to convert data in saidfirst data format to a second data format for wireless transmissionthrough the wireless communication path and to convert data in saidsecond data format to said first data format for transmission throughthe power line by said coupling device; and a wireless communicationdevice in communication with said signal converter, said wirelesscommunication device to communicate wireless communications through thewireless communication path to the second computer, the wirelesscommunications being in said second data format.
 35. The system asrecited in claim 34, wherein said signal converter comprises a firstmodem and a second modem.
 36. The system as recited in claim 35, whereinsaid signal converter further comprises a data router.
 37. The system asrecited in claim 35, wherein said coupling device comprises an inductor.38. The system as recited in claim 34, wherein the wirelesscommunications are formatted in compliance with an IEEE 802.11 protocol.